Bearings are widely needed mechanical components that are used to constrain relative motion between moving parts to only the desired motion. Ball bearings are used to reduce rotational friction and support radial and axial loads. Ball bearings are rolling-element bearings that use balls to maintain separation between bearing races. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. For a ball bearing to operate properly, it needs to be lubricated, e.g., by oil or grease.
Jewel bearings have been used in fine watches, gyroscopes and laboratory equipment for years. Jewel bearings are plain bearings wherein a metal spindle turns in a jewel-lined pivot hole. The hole is typically shaped like a torus and is slightly larger than the shaft diameter. Typically found in mechanical watches, a donut-shaped bearing is usually made of synthetic sapphire (ruby) and is press-fitted into a hole in the movement's supporting plate. A lubricant reservoir is nearby holding a lubricating oil that is in contact with the bearing shaft by capillary action.
The conventional design for jewel bearings for rotating equipment is to bore an oval shaped hole in the jewel (donut-shaped bearing) or provide a cone shaped pivot hole for a spindle to locate in. Such design cannot be used in any application requiring radial or thrust loading on the bearing because of the possibility of jewel fracturing. Thus, many potential applications such as high-speed turbines cannot use such a design.
U.S. Pat. No. 7,959,551 to Jarvik proposes blood pump bearings having a three post contact system to allow blood flow in a heart pump. This concept, while may be sufficient for the unique application, would not be satisfactory for supporting higher radial or thrust loads that would be presented in normal motor or turbine applications. Historically ball bearing technology has demonstrated the requirement of at least five-ball contact in the bearing races for even the smallest motors.
Thus, there is an ongoing need for improved bearing systems that do not require lubrication while at the same time have reduced heat generation and increased heat dissipation.